/*

    SDL - Simple DirectMedia Layer

    Copyright (C) 1997-2006 Sam Lantinga

    This library is free software; you can redistribute it and/or

    modify it under the terms of the GNU Lesser General Public

    License as published by the Free Software Foundation; either

    version 2.1 of the License, or (at your option) any later version.

    This library is distributed in the hope that it will be useful,

    but WITHOUT ANY WARRANTY; without even the implied warranty of

    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

    Lesser General Public License for more details.

    You should have received a copy of the GNU Lesser General Public

    License along with this library; if not, write to the Free Software

    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

    Sam Lantinga

    slouken@libsdl.org

*/

#include <pthread.h>

#include <semaphore.h>

#include "SDL_thread.h"

#include "SDL_timer.h"

/* Wrapper around POSIX 1003.1b semaphores */

#if MACOSX

#define USE_NAMED_SEMAPHORES 1

#endif /* MACOSX */

struct SDL_semaphore {

	sem_t *sem;

#if !USE_NAMED_SEMAPHORES

	sem_t sem_data;

#endif

};

/* Create a semaphore, initialized with value */

SDL_sem *SDL_CreateSemaphore(Uint32 initial_value)

{

	SDL_sem *sem = (SDL_sem *) SDL_malloc(sizeof(SDL_sem));

	if ( sem ) {

#if USE_NAMED_SEMAPHORES

		static int semnum = 0;

		char name[32];

		SDL_snprintf(name, SDL_arraysize(name), "/SDL_sem-%d-%4.4d", getpid(), semnum++);

		sem->sem = sem_open(name, O_CREAT, 0600, initial_value);

		if ( sem->sem == (sem_t *)SEM_FAILED ) {

			SDL_SetError("sem_open(%s) failed", name);

			SDL_free(sem);

			sem = NULL;

		} else {

			sem_unlink(name);

		}

#else

		if ( sem_init(&sem->sem_data, 0, initial_value) < 0 ) {

			SDL_SetError("sem_init() failed");

			SDL_free(sem);

			sem = NULL;

		} else {

			sem->sem = &sem->sem_data;

		}

#endif /* USE_NAMED_SEMAPHORES */

	} else {

		SDL_OutOfMemory();

	}

	return sem;

}

void SDL_DestroySemaphore(SDL_sem *sem)

{

	if ( sem ) {

#if USE_NAMED_SEMAPHORES

		sem_close(sem->sem);

#else

		sem_destroy(sem->sem);

#endif

		SDL_free(sem);

	}

}

int SDL_SemTryWait(SDL_sem *sem)

{

	int retval;

	if ( ! sem ) {

		SDL_SetError("Passed a NULL semaphore");

		return -1;

	}

	retval = SDL_MUTEX_TIMEDOUT;

	if ( sem_trywait(sem->sem) == 0 ) {

		retval = 0;

	}

	return retval;

}

int SDL_SemWait(SDL_sem *sem)

{

	int retval;

	if ( ! sem ) {

		SDL_SetError("Passed a NULL semaphore");

		return -1;

	}

	retval = sem_wait(sem->sem);

	if ( retval < 0 ) {

		SDL_SetError("sem_wait() failed");

	}

	return retval;

}

int SDL_SemWaitTimeout(SDL_sem *sem, Uint32 timeout)

{

	int retval;

	if ( ! sem ) {

		SDL_SetError("Passed a NULL semaphore");

		return -1;

	}

	/* Try the easy cases first */

	if ( timeout == 0 ) {

		return SDL_SemTryWait(sem);

	}

	if ( timeout == SDL_MUTEX_MAXWAIT ) {

		return SDL_SemWait(sem);

	}

	/* Ack!  We have to busy wait... */

	timeout += SDL_GetTicks();

	do {

		retval = SDL_SemTryWait(sem);

		if ( retval == 0 ) {

			break;

		}

		SDL_Delay(1);

	} while ( SDL_GetTicks() < timeout );

	return retval;

}

Uint32 SDL_SemValue(SDL_sem *sem)

{

	int ret = 0;

	if ( sem ) {

		sem_getvalue(sem->sem, &ret);

		if ( ret < 0 ) {

			ret = 0;

		}

	}

	return (Uint32)ret;

}

int SDL_SemPost(SDL_sem *sem)

{

	int retval;

	if ( ! sem ) {

		SDL_SetError("Passed a NULL semaphore");

		return -1;

	}

	retval = sem_post(sem->sem);

	if ( retval < 0 ) {

		SDL_SetError("sem_post() failed");

	}

	return retval;

}